The present invention relates to a method for producing xcex5-caprolactam from cyclohexanone oxime and, more specifically, a method for producing xcex5-caprolactam including the step of regenerating a zeolite or non-zeolitic material having lowered activity and a reactor for the method.
xcex5-caprolactam is an important chemical raw material used as a basic material for the production of nylon and the like. In a classical method for producing xcex5-caprolactam, cyclohexanone oxime is rearranged to xcex5-caprolactam in liquid phase using concentrated sulfuric acid or fuming sulfuric acid as a catalyst (liquid phase Beckmann rearrangement reaction).
However, in the method using a liquid phase Beckmann rearrangement reaction, a large amount of ammonia is required for neutralizing the sulfuric acid, and consequently, a large amount of ammonium sulfate is produced as a by-product and significant costs arise due to the necessary treatment thereof.
Therefore, a method in which cyclohexanone oxime in the gas phase is Beckmann-rearranged using a solid catalyst (gas phase Beckmann rearrangement reaction) has been studied for a long time.
In the gas phase Beckmann rearrangement reaction, a cyclohexanone oxime vapor is reacted in the presence of a solid catalyst. The solid catalyst may be, for example, (1) a silica gel catalyst (U.S. Pat. No. 2,234,566), (2) a silica alumina catalyst (GB Patent No. 831,972), or (3) a zeolite catalyst (Journal of Catalysis, Vol. 6, p. 247, 1996, and U.S. Pat. Nos. 4,359,421 and 5,741,904).
Among them, crystalline zeolite catalysts having various compositions have been developed. This is because zeolite catalysts are known to have excellent catalyst life and selectivity to xcex5-caprolactam as compared with silica-based catalysts and the like.
In the gas phase Beckmann rearrangement reaction, deposits are generated on the surface of the catalyst during the reaction, and as a result, the activity of the catalyst is gradually lowered. In order to regenerate the deactivated catalyst, the catalyst is burned under an oxygen-containing gas at a high temperature.
In the case of burning the catalyst with oxygen, however, a significant heat release is caused by oxidation, whereby the temperature of catalyst rises. Furthermore, when deposits such as carbonaceous components (i.e. so-called coke) present on the catalyst are oxidized, water is produced which adversely influences the catalyst itself.
One object of the present invention is to provide a method for producing xcex5-caprolactam by a catalyst regeneration method capable of suppressing the deterioration of the catalyst.
This object and other objectives are achieved by the present invention which provides a method for producing xcex5-caprolactam from cyclohexanone oxime by using a zeolite or non-zeolitic material as a catalyst under gas phase reaction conditions. The method includes a reaction step for converting cyclohexanone oxime into E -caprolactam in the presence of the zeolite or non-zeolitic material, and a regeneration step of treating the zeolite or non-zeolitic material with a non-oxidizing gas at a temperature of from about 100xc2x0 C. to about 600xc2x0 C.
Also, the present invention provides a reactor charged with a zeolite or non-zeolitic material and having a reaction zone in which the zeolite or non-zeolitic material is utilized as a catalyst. A regeneration zone is also provided for the zeolite or non-zeolitic material, and a means for circulating the zeolite or non-zeolitic material between the reaction zone and the regeneration zone.